Tuesday, July 04, 2017

Blargh. I saw this headline and I was suckered in. I thought there might actually be something novel behind it:: Human emotions really are affected by gut bacteria, new study suggests - ScienceAlert
But no - despite the headline, this is just about a paper that showed correlation between microbiome community patterns and various behavioral traits. Not a shred of cause vs effect tested. And yet despite that this is just a correlative study, the article just completely overstates the implications

"But it's clear that there's something going on between the organisms in our gut and the thoughts and feelings we experience, and the sooner we delve into this, the sooner we'll comprehend just how emotionally powerful our 'second brain' really is."

No no no no no and no. They do not show ANY connection between our thoughts and our microbiome. They just report a correlation. It could be that people with different thought patterns eat differently. Or people with different thought patterns exercise differently. Or $(#($(#@@ just abo9ut anything.
Alas, many other stories about this work also make false inferences.
See the Huffington Post for example: Your Gut Bacteria Really Do Affect Your Emotions

"A new study looked at how ‘microbiota’ bacteria in the human gut influences our emotional responses, as the evidence suggests there is a direct correlation between the two."

Again, no no no no and no. They do not study how microbiota influence emotional responses.

So one might ask - where could these news sources have gotten the idea that this was more than a correlative study? Hmm. I wonder. Maybe we should look for any press releases from UCLA? So I googled the lead authors name and found this:

Researchers have identified gut microbiota that interact with brain regions associated with mood and behavior.

No no no no no and no. There is no evidence that these gut microbiota interact with brain regions in any way. Later in the article there is a bit of a caveat -

Researchers do not yet know whether bacteria in the gut influence the development of the brain and its activity when unpleasant emotional content is encountered, or if existing differences in the brain influence the type of bacteria that reside in the gut.

But it is too little too late. And it is not actually accurate either. There are other possibilities - like there is a third factor that affects both the microbiome and the brain but where the brain and microbiome don't impact each other. What could that factor be? Oh I don't know - how about something called the immune system? It is just bad science to report that this has to be the gut affecting the brain or the brain affecting the gut.

And for this I am giving out a coveted "Overselling the Microbiome Award" to UCLA and their Press Office.